GB335198A - Improvements in or relating to electric signalling systems - Google Patents

Abstract

335,198. Lichter, I. J. March 19, 1929. Selective signalling-apparatus. - Relates to a signalling system more especially adapted for use in hospitals or other buildings for calling doctors or other persons located in different parts of the building. As shown different stations throughout the building are provided with a signal, preferably a visual signal SL, associated with a local switchboard G comprising a plurality of switches A - - E, 1 - - 5, different combinations of which are allocated to different persons. In the arrangement shown the switches are used in pairs so that 25 different persons may be called. The various stations equipments are connected in parallel to a central station switchboard H, comprising individual call switches A1 - - E5 and their associated lamps, by two groups of conductors AL - - EL, 1 - - 5. A manually or automatically operated switch IB at the central station connects the power supply F successively to the line wires AL - - EL and to the lamp and switch groups A - - E. Assuming a person whose designation is " A2 " enters station G, corresponding switches A, 2 are operated and remain depressed while the person remains at the station. Switches A, 2 prepare circuits for the signalling device SL and if it is desired to notify the person that his presence is required elsewhere, the corresponding switch A2 at the central station is operated to complete the signalling circuit. Upon each rotation of the central station switch IB the remote station signalling relay is operated over switch A to complete the signalling circuit over switch 2 and central station switch and lamp A2. The system also enables different persons to be called simultaneously.